Vision constitutes an interesting domain, or range of domains, for debate over the extended mind thesis, the idea that minds physically extend beyond the boundaries of the body. In part this is because vision and visual experience more particularly are sometimes presented as a kind of line in the sand for what we might call externalist creep about the mind: once all reasonable concessions have been made to externalists about the mind, visual experience marks a line beyond which lies a (...) safe haven for individualists. Here I want to put a little more pressure on such a view of visual experience, as well as to offer a more constructive, positive argument in defense of the idea of extended vision. (shrink)

The concept of microgenesis refers to the development on a brief present-time scale of a percept, a thought, an object of imagination, or an expression. It defines the occurrence of immediate experience as dynamic unfolding and differentiation in which the ‘germ’ of the final experience is already embodied in the early stages of its development. Immediate experience typically concerns the focal experience of an object that is thematized as a ‘figure’ in the global field of consciousness; this can involve a (...) percept, thought, object of imagination, or expression (verbal and/or gestural). Yet, whatever its modality or content, focal experience is postulated to develop and stabilize through dynamic differentiation and unfolding. Such a microgenetic description of immediate experience substantiates a phenomenological and genetic theory of cognition where any process of perception, thought, expression or imagination is primarily a process of genetic differentiation and development, rather than one of detection (of a stimulus array or information), transformation, and integration (of multiple primitive components) as theories of cognitivist kind have contended. My purpose in this essay is to provide an overview of the main constructs of microgenetic theory, to outline its potential avenues of future development in the field of cognitive science, and to illustrate an application of the theory to research, using visual processes in reading as an example. (shrink)

What is Computational Intelligence (CI) and what are its relations with Artificial Intelligence (AI)? A brief survey of the scope of CI journals and books with ``computational intelligence'' in their title shows that at present it is an umbrella for three core technologies (neural, fuzzy and evolutionary), their applications, and selected fashionable pattern recognition methods. At present CI has no comprehensive foundations and is more a bag of tricks than a solid branch of science. The change of focus from methods (...) to challenging problems is advocated, with CI defined as a part of computer and engineering sciences devoted to solution of non-algoritmizable problems. In this view AI is a part of CI focused on problems related to higher cognitive functions, while the rest of the CI community works on problems related to perception and control, or lower cognitive functions. Grand challenges on both sides of this spectrum are addressed. (shrink)

In preparation for examining the place of introspective evidence in scientific psychology, the chapter begins by clarifying what introspection has been supposed to show, and why some concluded that it couldn't deliver. This requires a brief excursus into the various uses to which introspection was supposed to have been put by philosophers and psychologists in the modern period, together with a summary of objections. It then reconstructs some actual uses of introspection (or related techniques, differently monikered) in the early days (...) of experimental psychology. It distinguishes broader and narrower conceptions of introspection and argues that recent critics have tended to misdescribe how introspection was supposed to work. Drawing upon the broader conception of introspection, it argues that introspective reports are ineliminable in perceptual psychology. It concludes with some examples of such ineliminable uses of introspective reports in both earlier and recent perceptual psychology. (shrink)

It is a common assumption among philosophers of perception that phenomenal colors are exhaustively characterized by the three phenomenal dimensions of the color solid: hue, saturation and lightness. The hue of a color is its redness, blueness or yellowness, etc. The saturation of a color refers to the strength of its hue in relation to gray. The lightness of a color determines its relation to black and white. In this paper, I argue that the phenomenology of shadows forces us to (...) consider illumination as an additional dimension of phenomenal colors. For this purpose, I will first introduce two different interpretations of shadow-experiences, which Chalmers has called the simple and the complex interpretations, and show that they both fail to account for important phenomenal facts about shadow-experiences. I will then introduce my own alternative interpretation based on the idea that illumination is a dimension of phenomenal colors and explain how it can account for these facts. (shrink)

Recognitional concepts have the following characteristic property: thinkers are disposed to apply them to objects merely on the basis of undergoing certain perceptual experiences. I argue that a prominent strategy for defending the existence of constitutive connections among concepts, which appeals to thinkers’ semantic-cum-conceptual intuitions, cannot be used to defend the existence of recognitional concepts. I then outline and defend an alternative argument for the existence of recognitional concepts, which appeals to certain psychological laws.

This article addresses Paul Churchland’s attempt to identify colors with surface reflectance spectra. Of particular concern is Churchland’s novel method of approximating surface reflectance spectra. While those approximations are generated by objective means and yield a striking match with human phenomenological color space, they are not physically meaningful. The reason for this is that the method used to produce the approximations induces equivalence classes on surface reflectances that are not invariant under physically appropriate changes of measurement convention. This result undermines (...) Churchland’s proposed response to the objection from metamers commonly raised against color physicalism, as his surface reflectance approximations are supposed to provide an objective, physical unifying basis for metamers. *Received December 2007; revised July 2009. †To contact the author, please write to: Department of Logic and Philosophy of Science, School of Social Sciences, 3151 Social Science Plaza A, University of California, Irvine, CA 92697; e‐mail: [email protected]. (shrink)

This chapter presents an overview of several recent developments in vision science, and outlines some of their implications for the management of visual attention in graphic displays. These include ways of sending attention to the right item at the right time, techniques to improve attentional efficiency, and possibilities for offloading some of the processing typically done by attention onto nonattentional mechanisms. In addition it is argued that such techniques not only allow more effective use to be made of visual attention, (...) but also open up new possibilities for human-machine interaction. (shrink)

Perceptual attention is essential to both thought and agency, for there is arguably no demonstrative thought or bodily action without it. Psychologists and philosophers since William James have taken attention to be a ubiquitous and distinctive form of consciousness, one that leaves a characteristic mark on perceptual experience. As a process of selecting specific perceptual inputs, attention influences the way things perceptually appear. It may then seem that it is a specific feature of perceptual representation that constitutes what it is (...) like to consciously attend to an object. In fact conscious attention is more complicated. In what follows, I argue that the phenomenology of conscious attention to what is perceived involves not just a way of perceptually locking on to a specific object. It necessarily involves a way of cognitively locking on to it as well. (shrink)

One popular materialist response to the explanatory gap identifies phenomenal concepts with type-demonstrative concepts. This kind of response, however, faces a serious challenge: that our phenomenal concepts seem to provide a richer characterization of their referents than just the demonstrative characterization of 'that quality'. In this paper, I develop a materialist account that beefs up the contents of phenomenal concepts while retaining the idea that these contents contain demonstrative elements. I illustrate this account by focusing on our phenomenal concepts of (...) phenomenal colour. The phenomenal colours stand in a similarity space relative to one another in virtue of being complex qualities—qualities that contain saturation, lightness, and various aspects of hue as component elements. Our phenomenal concepts, in turn, provide a demonstrative characterization of each of these component elements as well as a description of how much of that element is present in a given phenomenal colour. The result is an account where phenomenal concepts contain demonstrative elements and yet provide a significantly richer characterization of the intrinsic nature of their referents than just 'that quality'. (shrink)

Frank Jackson’s knowledge argument (KA) aims to prove, by means of a thought experiment concerning the hypothetical scientist Mary, that conscious experiences have non-physical properties, called qualia. Mary has complete scientific knowledge of colours and colour vision without having had any colour experience. The central intuition in the KA is that, by seeing colours, Mary will learn what it is like to have colour experiences. Therefore, her scientific knowledge is incomplete, and conscious experiences have qualia. In this paper I consider (...) an objection to the KA raised by Daniel Dennett. He maintains that the KA is vitiated by Jackson’s account of Mary’s scientific knowledge. While endorsing this criticism, I will defend the plausibility and relevance of the type of strategy involved in the KA by offering an account of Mary’s scientific knowledge. This account involves formulating a reasonable and not immediately false version of the physicalist thesis with regard to colour experiences. Whether this version of the KA is successful against this type of physicalism is not investigated here. (shrink)

An important class of teleological theories cannot explain the representational content of visual states because they fail to address the relationship between the world, projected retinal stimuli, and perception. A different approach for achieving a naturalized theory of visual content is offered that rejects the traditional internalism/externalism debate in favor of what is termed “empirical externalism.” This position maintains that, while teleological considerations can underwrite a broad understanding of representation, the content of visual representation can only be determined empirically according (...) to accumulated past experience. A corollary is that a longstanding problem concerning the indeterminacy of visual content is dissolved. (shrink)

In this paper, I explore and defend the idea that we have epistemic responsibilities with respect to our visual searches, responsibilities that are far more fine-grained and interesting than the trivial responsibilities to keep our eyes open and “look hard”. In order to have such responsibilities, we must be able to exert fine-grained and interesting forms of control over our visual searches. I present both an intuitive case and an empirical case for thinking that we do, in fact, have such (...) forms of control over our visual searches. I then show how these forms of control can be used to aim the visual beliefs that result from our searches towards various epistemic goals. (shrink)

In this paper, I defend a representationalist account of the phenomenal character of color experiences. Representationalism, the thesis that phenomenal character supervenes on a certain kind of representational content, so-called phenomenal content, has been developed primarily in two different ways, as Russellian and Fregean representationalism. While the proponents of Russellian and Fregean representationalism differ with respect to what they take the contents of color experiences to be, they typically agree that colors are exhaustively characterized by the three dimensions of the (...) color solid: hue, saturation, and lightness. I argue that a viable version of representationalism needs to renounce this restriction to three dimensions and consider illumination to be a genuine phenomenal dimension of color. My argument for this thesis falls into two parts. I first consider the phenomenon of color constancy in order to show that neither Russellian nor Fregean representationalism can do justice to the phenomenal significance of local illumination. I subsequently formulate a version of representationalism that accounts for illumination by taking it as a phenomenal dimension of color. (shrink)

Fallibilists about looks deny that the relation of looking the same as is non-transitive. Regarding familiar examples of coloured patches suggesting that such a relation is non-transitive, they argue that, in fact, indiscriminable adjacent patches may well look different, despite their perceptual indiscriminability: it’s just that we cannot notice the relevant differences in the chromatic appearances of such patches. In this paper, I present an argument that fallibilism about looks requires commitment to an empirically false consequence. To succeed in deflecting (...) putative cases of non-transitivity, fallibilists would have to claim that there can’t be any perceptual limitations of any kind on human chromatic discrimination. But there are good reasons to think such limitations exist. (shrink)

Accurate perception of moving objects would be useful; accurate visually guided action is crucial. Visual motion across the scene influences perceived object location and the trajectory of reaching movements to objects. In this commentary, I propose that the visual system assigns the position of any object based on the predominant motion present in the scene, and that this is used to guide reaching movements to compensate for delays in visuomotor processing.

Evidence for motion extrapolation at motion offset is scarce. In contrast, there is abundant evidence that subjects mentally extrapolate the future trajectory of weak motion signals at motion offset. Further, pointing movements overshoot at motion offset. We believe that mental and sensorimotor extrapolation is sufficient to solve the problem of perceptual latencies. Both present the advantage of being much more flexible than motion extrapolation.

Nijhawan's theory rests on the assumption that transient signals compete with predictive signals to generate the visual percept. We describe experiments that show that this assumption is incorrect. Our results are consistent with an alternative theory that proposes that vision is instead postdictive, in that the perception of an event is influenced by occurrences after the event.

Many viewers presented with a round plate tilted to their line of sight will report that they see a round plate that looks elliptical from their perspective. Alva Noë thinks that we should take reports of this kind as adequate descriptions of the phenomenology of spatial experiences. He argues that his so‐called enactive or sensorimotor account of spatial perceptual content explains why both the plate's circularity and its elliptical appearance are phenomenal aspects of experience. In this paper, I critique the (...) phenomenal adequacy of Noë's sensorimotor account of spatial perceptual content. I begin by showing that some of its central claims are in conflict with the phenomenology of perceptual experience. I then argue that shape appearances have no phenomenal reality, thus undermining this central motivation for his account. (shrink)

The purpose of this paper is to defend what I call the action-oriented coding theory (ACT) of spatially contentful visual experience. Integral to ACT is the view that conscious visual experience and visually guided action make use of a common subject-relative or 'egocentric' frame of reference. Proponents of the influential two visual systems hypothesis (TVSH), however, have maintained on empirical grounds that this view is false (Milner & Goodale, 1995/2006; Clark, 1999; 2001; Campbell, 2002; Jacob & Jeannerod, 2003; Goodale & (...) Milner, 2004). One main source of evidence for TVSH comes from behavioral studies of the comparative effects of size-contrast illusions on visual awareness and visuo- motor action. This paper shows that not only is the evidence from illusion studies inconclusive, there is a better, ACT-friendly interpretation of the evidence that avoids serious theoretical difficulties faced by TVSH. (shrink)

Recent developments in vision science have resulted in several major changes in our understanding of human visual perception. For example, attention no longer appears necessary for "visual intelligence"--a large amount of sophisticated processing can be done without it. Scene perception no longer appears to involve static, general-purpose descriptions, but instead may involve dynamic representations whose content depends on the individual and the task. And vision itself no longer appears to be limited to the production of a conscious "picture"--it may also (...) guide processes outside the conscious awareness of the observer. (shrink)

Colors are of philosophical interest for two kinds of reason. One is that colors comprise such a large and important portion of our social, personal and epistemological lives and so a philosophical account of our concepts of color is highly desirable. The second reason is that trying to fit colors into accounts of metaphysics, epistemology and science leads to philosophical problems that are intriguing and hard to resolve. Not surprisingly, these two kinds of reasons are related. The fact that colors (...) are so significant in their own right, makes more pressing the philosophical problems of fitting them into more general metaphysical and epistemological frameworks. (shrink)

This article compares the ability to track individuals lacking mental states with the ability to track intentional agents. It explains why reference to individuals raises the problem of explaining how cognitive agents track unique individuals and in what sense reference is based on procedures of perceptual-motor and epistemic tracking. We suggest applying the notion of singular-files from theories in perception and semantics to the problem of tracking intentional agents. In order to elucidate the nature of agent-files, three views of the (...) relation between object- and agent-tracking are distinguished: the Independence, Deflationary and Organism-Dependence Views. The correct view is argued to be the latter, which states that perceptual and epistemic tracking of a unique human organism requires tracking both its spatio-temporal object-properties and its agent-properties. (shrink)

This paper will argue that there is no such thing as introspective access to judgments and decisions. It won't challenge the existence of introspective access to perceptual and imagistic states, nor to emotional feelings and bodily sensations. On the contrary, the model presented in Section 2 presumes such access. Hence introspection is here divided into two categories: introspection of propositional attitude events, on the one hand, and introspection of broadly perceptual events, on the other. I shall assume that the latter (...) exists while arguing that the former doesn't (or not in the case of judgments and decisions, at least). Section 1 makes some preliminary points and distinctions, and outlines the scope of the argument. Section 2 presents and motivates the general model of introspection that predicts a divided result. Section 3 provides independent evidence for the conclusion that judgments and decisions aren't introspectable. Section 4 then replies to a number of objections to the argument, the most important of which is made from the perspective of so-called "dual systems theories" of belief formation and decision making. The upshot is a limited form of eliminativism about introspection, in respect of at least two core categories of propositional attitude. (shrink)

What is the relation between Kanizsa's bias towards convexity and the Gestaltists' demonstrations that perceptual organization obeys a principle of pragnänz, or simplicity? Why should either kind of bias exist? Textbook accounts assign no functional role for these biases. Geon theory (Biederman 1987) proposes that we can understand these biases in terms of fundamental processes by which complex objects are decomposed into convex (or singly concave) regions at points of matched cusps according to the transversality regularity (Hoffman and Richards 1985). (...) Such decomposition yields simple, convex parts segmented between the concavities. A shape that contains concavities is generally regarded as complex insofar as it can be decomposed into the regions, or parts, between the concavities. It is these simple parts that are the stable elements of shape, not the whole object. In fact, geon theory leads to the expectation that shape recognition proceeds most efficiently when the parts are good (in the pragnänz sense) but the object is bad! (shrink)

Despite a wealth of data we still have no clear idea what color experiences represent. In fact, color experiences vary with so many factors that it has been claimed that they do not represent anything at all. The primary challenge for any representational account of color experience is to accommodate the various psychophysical results that demonstrate that color appearance depends not only on the spectral nature of the target but also on the spectral, spatial and figural nature of the surround. (...) A number of theorists have proposed that this dependence is an aspect of the visual system's constancy mechanism. However this does not in and of itself tell us what, if anything, is represented in color experience. Ultimately the answer to this question will be informed by one's theory of representational content. I will argue that adopting a molecular scheme of representation enables the development of an account of the represented object of color experience that can do justice to the psychophysical data. (shrink)

Many alleged counter-examples to intentionalism, the thesis that the phenomenology of perceptual experiences of a given sense modality supervenes on the contents of experiences of that modality, can be avoided by adopting a liberal view of the sorts of properties that can be represented in perceptual experience. I argue that there is a class of counter-examples to intentionalism, based on shifts in attention, which avoids this response. A necessary connection between the contents and phenomenal characters of perceptual experiences can be (...) preserved by distinguishing perceptual phenomenology from the phenomenology of attention; but even if this distinction is viable, these cases put pressure on the thesis that phenomenal character can, in general, be explained in terms of mental representation. (shrink)

Neuropsychological findings used to motivate the "two visual systems" hypothesis have been taken to endanger a pair of widely accepted claims about spatial representation in conscious visual experience. The first is the claim that visual experience represents 3-D space around the perceiver using an egocentric frame of reference. The second is the claim that there is a constitutive link between the spatial contents of visual experience and the perceiver's bodily actions. In this paper, I review and assess three main sources (...) of evidence for the two visual systems hypothesis. I argue that the best interpretation of the evidence is in fact consistent with both claims. I conclude with some brief remarks on the relation between visual consciousness and rational agency. (shrink)

My overall aim here is to intersect two issues central to Max Velmans' wide-ranging paper. The first concerns one of the most vexing problems in consciousness research — how best to approach the terms 'mental' and 'physical'. The second looks at the phenomenology of volition, and the degree to which information presumably necessary for making voluntary conscious decisions is, or is not, present in consciousness. Velmans offers three general reasons to motivate his position: the physical world is 'causally closed' to (...) the influence of consciousness; consciousness does not contain the information necessary for making volitional decisions; conscious feelings of volition occur before the acts they supposedly cause. It seems to me that none of this holds up well under scrutiny. I will concentrate on the first two reasons, since I think they involve more basic and widespread aspects of consciousness research. (shrink)

Recent advances in our understanding of visual perception have shown it to be a far more complex and counterintuitive process than previously believed. Several important consequences follow from this. First, the design of an effective statistical graphics system is unlikely to succeed based on intuition alone; instead, it must rely on a more sophisticated, systematic approach. The basic elements of such an approach are outlined here, along with several design principles. An overview is then given of recent advances in our (...) understanding of visual perception, including rapid perception, visual attention, and scene perception. It then is argued that the mechanisms involved can be successfully harnessed to allow data to be displayed more effectively than at present. Several directions of development are discussed, including effective use of visual attention, the display of dynamic information, and the effective use of nonattentional and nonconscious perceptual systems. (shrink)

Among psychologists and vision scientists,binocular rivalry has enjoyed sustainedinterest for decades dating back to the 19thcentury. In recent years, however, rivalry''saudience has expanded to includeneuroscientists who envision rivalry as a tool for exploring the neural concomitants ofconscious visual awareness and perceptualorganization. For rivalry''s potential to berealized, workers using this tool need toknow details of this fascinating phenomenon,and providing those details is the purpose ofthis article. After placing rivalry in ahistorical context, I summarize major findingsconcerning the spatial characteristics and thetemporal dynamics (...) of rivalry, discuss two majortheoretical accounts of rivalry ( eye vs stimulus rivalry) and speculate on possibleneural concomitants of binocular rivalry. (shrink)

There is a strong philosophical intuition that direct study of the brain can and will constrain the development of psychological theory. When this intuition is tested against case studies on the neurophysiology and psychology of perception and memory, it turns out that psychology has led the way toward knowledge of neurophysiology. An abstract argument is developed to show that psychology can and must lead the way in neuroscientific study of mental function. The opposing intuition is based on mainly weak arguments (...) about the fundamentality or objectivity of physics or physiology in relation to psychology. -/- Philosophy of Science, Vol. 67, Supplement. Proceedings of the 1998 Biennial Meetings of the Philosophy of Science Association. Part II: Symposia Papers (Sep., 2000). (shrink)

To appear in the Cambridge Handbook to Cognitive Science, eds. Ramsey and Frankish.

The chapter argues from an ethology-inspired internalist perspective that ‘colour’ is not a homogeneous and autonomous attribute, but rather plays different roles in different conceptual forms underlying perception. It discusses empirical and theoretical evidence that indicates that core assumptions underlying orthodox conceptions are grossly inadequate. The assumptions pertain to the idea that colour is a kind of autonomous and unitary attribute. It is regarded as unitary or homogeneous by assuming that its core properties do not depend on the type of (...) ‘perceptual object’ to which it pertains and that‘colour per se’ constitutes a natural attribute in the functional architecture of the perceptual system. It is regarded as autonomous by assuming that it can be studied in isolation of other perceptual attributes. More generally, the chapter argues on the bases of corresponding empirical and theoretical evidence that perception cannot be understood as the ‘recovery’ of physical world structure from sensory structure by input-based computational processes. Rather, the sensory input serves as a kind of sign for biologically relevant aspects of the external world that activates biologically given conceptual forms with their internal parameters. Although the sensory input is a causally necessary requirement for the activation of conceptual forms, the perceptual computations triggered are under the control of an internal programme based on a set of conceptual forms. (shrink)

According to colour irrealism, material objects do not have colour; they only appear to have colour. The appeal of this view, prominent among philosophers and scientists alike, stems in large part from the conviction that scientific explanations of colour facts do not ascribe colour to material objects. To explain why objects appear to have colour, for instance, we need only appeal to surface reflectance properties, properties of light, the neurophysiology of observers, etc. Typically attending colour irrealism is the error theory (...) of ordinary colour judgement: ordinary judgements in which colour is ascribed to a material object are, strictly speaking, false. In this paper, I claim that colour irrealists who endorse the error theory cannot explain how we acquire colour concepts (yellow, green, etc.), concepts they must acknowledge we do possess. Our basic colour concepts, I argue, could not be phenomenal concepts that we acquire by attending to the colour properties of our experience. And, I explain, all other plausible explanations render colour concepts such that our ordinary colour judgements involving them are often true. Given the explanatory considerations upon which the irrealist's position is based, this is a severe problem for colour irrealism. (shrink)

There is nothing in this World constant but Inconstancy. [Swift 1711: 258] In this paper I argue that two standard characterizations of colour constancy are inadequate to the phenomenon. This inadequacy matters, since, I contend, philosophical appeals to colour constancy as a way of motivating illumination-independent conceptions of colour turn crucially on the shortcomings of these characterizations. After critically reviewing the standard characterizations, I provide a novel counterfactualist understanding of colour constancy, argue that it avoids difficulties of its traditional rivals, (...) and defend it from objections. Finally, I show why, on this improved understanding, colour constancy does not have the philosophical consequences that have been claimed for it in the literature. (shrink)

The experience of looking at a tilted penny involves a “phenomenological doubleness” in that it simultaneously seems to be of something circular and of something elliptical. In this paper, I investigate the phenomenological doubleness of this experience by comparing it to another case of phenomenological doubleness––the phenomenological doubleness of seeing an object in a painting. I begin by pointing out some striking similarities between the phenomenological characters of these two experiences. I then argue that these phenomenological characters have a common (...) explanation. More specifically, I argue that the psychological mechanism that explains the phenomenological doubleness of the experience of seeing an object in a painting can be extended to also explain the phenomenological doubleness of the experience of seeing a tilted penny. (shrink)

This paper examines the status of unattended visual stimuli in the light of recent work on the role of attention in visual perception. Although the question of whether attention is required for visual experience seems very interesting, this paper argues that there currently is no good reason to take a stand on the issue. Moreover, it is argued that much of the allure of that question stems from a continued attachment to the defective ‘inner picture view’ of experience and a (...) mistaken notion that the ultimate goal of vision is to produce visual experience. The paper considers a promising general account of the content and structure of vision and presents reasons for not taking that account to be committed to any substantive claims about the experiential status of unattended visual stimuli. Also addressed are the active nature of vision and the role of vision in enabling our ecological success. These considerations highlight that visual experience is not the whole of vision and that a much more important question about unattended visual stimuli than whether they are consciously experienced is what contribution they make to how we interact with the world. (shrink)

Computational theories of vision typically rely on the analysis of two aspects of human visual function: (1) object and shape recognition (2) co-calibration of sensory measurements. Both these approaches are usually based on an inverse-optics model, where visual perception is viewed as a process of inference from a 2D retinal projection to a 3D percept within a Euclidean space schema. This paradigm has had great success in certain areas of vision science, but has been relatively less successful in understanding perceptual (...) representation, namely, the nature of the perceptual encoding. One of the drawbacks of inverse-optics approaches has been the difficulty in defining the constraints needed to make the inference computationally tractable (e.g. regularity assumptions, Bayesian priors, etc.). These constraints, thought to be learned assumptions about the nature of the physical and optical structures of the external world, have to be incorporated into any workable computational model in the inverse-optics paradigm. But inference models that employ an inverse optics plus structural assumptions approach inevitably result in a na. (shrink)

There has been some recent optimism that addressing the question of how we distinguish sensory modalities will help us consider whether there are limits on a scientific understanding of perceptual states. For example, Block has suggested that the way we distinguish sensory modalities indicates that perceptual states have qualia which at least resist scientific characterization. At another extreme, Keeley argues that our common-sense way of distinguishing the senses in terms of qualitative properties is misguided, and offers a scientific eliminativism about (...) common-sense modalities which avoids appeal to qualitative properties altogether. I’ll argue contrary to Keeley that qualitative properties are necessary for distinguishing senses, and contrary to Block that our common-sense distinction doesn’t indicate that perceptual states have qualia. A non-qualitative characterization of perceptual states isn’t needed to avoid the potential limit on scientific understanding imposed by qualia. (shrink)

Visual space can be distinguished from physical space. The first is found in visual experience, while the second is defined independently of perception. Theorists have wondered about the relation between the two. Some investigators have concluded that visual space is non-Euclidean, and that it does not have a single metric structure. Here it is argued that visual space exhibits contraction in all three dimensions with increasing distance from the observer, that experienced features of this contraction are not the same as (...) would be the experience of a perspective projection onto a fronto-parallel plane, and that such contraction is consistent with size constancy. These properties of visual space are different from those that would be predicted if spatial perception resulted from the successful solution of the inverse problem. They are consistent with the notion that optical constraints have been internalized. More generally, they are also consistent with the notion that visual spatial structures bear a resemblance relation to physical spatial structures. This notion supports a type of representational relation that is distinct from mere causal correspondence. The reticence of some philosophers and psychologists to discuss the structure of phenomenal space is diagnosed in terms of the simple materialism and the functionalism of the 1970s and 1980s. (shrink)

A traditional explanation that dates back to Aristotle is that we access color in one perceptual modality only, whereas shape we perceive via two different modalities: visual and tactile. Two independent modalities make possible a verification of our percepts which is not possible for qualities accessed in one modality only.